drm/amd/powerplay: honor hw limit on fetching metrics data

Request too frequently may get corrupt data.
Signed-off-by: Evan Quan <evan.quan@amd.com>
Reviewed-by: Feifei Xu <Feifei.Xu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/powerplay/inc/amdgpu_smu.h

@@ -403,6 +403,9 @@ struct smu_context
 	uint32_t default_power_profile_mode;
 
 	uint32_t smc_if_version;
+
+	unsigned long metrics_time;
+	void *metrics_table;
 };
 
 struct pptable_funcs {

drivers/gpu/drm/amd/powerplay/smu_v11_0.c

@@ -369,6 +369,13 @@ static int smu_v11_0_init_power(struct smu_context *smu)
 		return -ENOMEM;
 	smu_power->power_context_size = sizeof(struct smu_11_0_dpm_context);
 
+	smu->metrics_time = 0;
+	smu->metrics_table = kzalloc(sizeof(SmuMetrics_t), GFP_KERNEL);
+	if (!smu->metrics_table) {
+		kfree(smu_power->power_context);
+		return -ENOMEM;
+	}
+
 	return 0;
 }
 
@@ -379,7 +386,9 @@ static int smu_v11_0_fini_power(struct smu_context *smu)
 	if (!smu_power->power_context || smu_power->power_context_size == 0)
 		return -EINVAL;
 
+	kfree(smu->metrics_table);
 	kfree(smu_power->power_context);
+	smu->metrics_table = NULL;
 	smu_power->power_context = NULL;
 	smu_power->power_context_size = 0;
 
@@ -1093,6 +1102,26 @@ static int smu_v11_0_start_thermal_control(struct smu_context *smu)
 	return ret;
 }
 
+static int smu_v11_0_get_metrics_table(struct smu_context *smu,
+		SmuMetrics_t *metrics_table)
+{
+	int ret = 0;
+
+	if (!smu->metrics_time || time_after(jiffies, smu->metrics_time + HZ / 1000)) {
+		ret = smu_update_table(smu, TABLE_SMU_METRICS,
+				(void *)metrics_table, false);
+		if (ret) {
+			pr_info("Failed to export SMU metrics table!\n");
+			return ret;
+		}
+		memcpy(smu->metrics_table, metrics_table, sizeof(SmuMetrics_t));
+		smu->metrics_time = jiffies;
+	} else
+		memcpy(metrics_table, smu->metrics_table, sizeof(SmuMetrics_t));
+
+	return ret;
+}
+
 static int smu_v11_0_get_current_activity_percent(struct smu_context *smu,
 						  uint32_t *value)
 {
@@ -1102,7 +1131,7 @@ static int smu_v11_0_get_current_activity_percent(struct smu_context *smu,
 	if (!value)
 		return -EINVAL;
 
-	ret = smu_update_table(smu, TABLE_SMU_METRICS, (void *)&metrics, false);
+	ret = smu_v11_0_get_metrics_table(smu, &metrics);
 	if (ret)
 		return ret;
 
@@ -1139,7 +1168,7 @@ static int smu_v11_0_get_gpu_power(struct smu_context *smu, uint32_t *value)
 	if (!value)
 		return -EINVAL;
 
-	ret = smu_update_table(smu, TABLE_SMU_METRICS, (void *)&metrics, false);
+	ret = smu_v11_0_get_metrics_table(smu, &metrics);
 	if (ret)
 		return ret;